CN1920592A - Phase correction method and apparatus, magnetic resonance imaging method and apparatus - Google Patents
Phase correction method and apparatus, magnetic resonance imaging method and apparatus Download PDFInfo
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- CN1920592A CN1920592A CNA2006101215260A CN200610121526A CN1920592A CN 1920592 A CN1920592 A CN 1920592A CN A2006101215260 A CNA2006101215260 A CN A2006101215260A CN 200610121526 A CN200610121526 A CN 200610121526A CN 1920592 A CN1920592 A CN 1920592A
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
- G01R33/56563—Correction of image distortions, e.g. due to magnetic field inhomogeneities caused by a distortion of the main magnetic field B0, e.g. temporal variation of the magnitude or spatial inhomogeneity of B0
Abstract
To calculate a precise phase map even when there is a local phase disturbance and perform this phase correction, an image acquired by magnetic resonance imaging is subjected to low pass filtering 702, pixel positions 704 for which the ratio of a value after filtering to a value before filtering does not exceed a predetermined ratio are detected, a phase distribution excluding pixel data at these positions is calculated, and the phases at the excluded pixel positions are estimated from the phases of neighboring pixel positions to provide compensation so as to complete a phase map.
Description
The application's denomination of invention that to be applicant GE Medical System Global Technology Co., Ltd. submit on October 23rd, 2000 is divided an application for the Chinese patent application No.20001318799's of " PHASE DISTRIBUTION and method for correcting phase and device and MR imaging method and device ".
Technical field
The present invention relates to phase distribution measuring method and apparatus, method for correcting phase and device, reach MR imaging method and device, more particularly, relate to the PHASE DISTRIBUTION that is used to measure the image that obtains by magnetic resonance imaging method and apparatus, relate to be used for based on the PHASE DISTRIBUTION of measuring come correcting pixel data phase place method and apparatus and relate to MR imaging method and the device of acquisition based on the image of the water of phase correction pixel data and lipides.
Background technology
In MR imaging apparatus, form the stationary magnetic field in the space that holds imaging object, form gradient magnetic and high frequency magnetic field in the space, stationary magnetic field, form (reconstruct) image according to the magnetic resonance signal that spin produced of imaging object.Because chemical shift, the magnetic resonance signal frequency of lipides is different with the magnetic resonance signal frequency of water, therefore can utilize phase differential respectively to water and lipides imaging according to the frequency difference.
The phase place of magnetic resonance signal is influenced by the heterogeneity of stationary magnetic field intensity, therefore magnetic field is heteropical to be influenced in order respectively water and lipides imaging not to be subjected to, calculate the heteropical PHASE DISTRIBUTION in expression stationary magnetic field, be phase diagram, and carry out the phase correction of image in view of the above.
Obtain phase diagram by the phase place of each pixel being calculated with the view data of complex representation.In order to obtain accurate phase diagram, at first handle image and remove noise with low-pass filter.
Fig. 1 illustrates the notion of the phase diagram of typical one dimension image.Get the center of the initial point of phase diagram as the stationary magnetic field.The phase place of initial point is 0.This figure is a phase diagram, wherein stationary magnetic field intensity have linear gradient and phase place according to initial point apart from linear change.When phase place surpass+during π, it is got back to-the π side, and when it during above-π, it is got back to+the π side, shown in this figure (a).In other words, produce phase place rollback (wrap around).
Therefore, carrying out rollback in the part that has rollback proofreaies and correct, is uncoiling (unwrapping), so that obtain not having the phase diagram of rollback, shown in this figure (b).
Whether whether 2 π detect rollback occur according to the absolute value of the phase differential of the view data of neighbor, for the pixel that detects rollback, 2 π are added to the symbol with the opposite in sign of phase differential on the phase place of view data of pixel.
When carrying out low-pass filtering as the preliminary step of calculating phase diagram and to image, because the magnetized variation of imaging object, because the phase change of lipides, because blood circulation or health moves or the mirage phantom of noise is disturbed pixel data partly in some position.In these positions, it seems to seem to have the rollback phase state, but can not obtain accurate phase diagram by carrying out uncoiling in view of the above.
In addition, if the unevenness in magnetic field is non-linear, then phase diagram comprises high order component.Low-pass filtering must be set,, but be not easy to carry out this low-pass filtering setting so that remove these high order components.
Summary of the invention
The purpose of this invention is to provide the phase distribution measuring method and apparatus, even it also can calculate accurate phase diagram when existing local phase to disturb, the method for correcting phase and the device of the phase diagram that utilizes this calculating are provided, and produce MR imaging method and the device of carrying out this phase correction.
Another purpose of the present invention provides the method and apparatus of phase correction, its feasible phase correction that comprises high fdrequency component easily; And the method and apparatus of magnetic resonance imaging is provided, is used to carry out such correction.
The present invention who comes from an aspect that addresses the above problem is a kind of phase distribution measuring method, and it comprises the steps: the image that obtains by magnetic resonance imaging is carried out low-pass filtering; The pixel data of each respective pixel by image before the low-pass filtering relatively and the image after the low-pass filtering detects such location of pixels: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; The pixel data of getting rid of detected location of pixels calculates PHASE DISTRIBUTION according to image before the low-pass filtering or the image after the low-pass filtering; And compensate by the phase place of the pixel estimating from the phase place of neighborhood pixels position to be excluded described in calculated PHASE DISTRIBUTION.
In coming from this present invention on the one hand, compare before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, there is the location of pixels of phase interference in detection, calculating is with the excluded phase diagram of the pixel data of these location of pixels, phase place by the location of pixels estimating from the phase place of neighborhood pixels position to be excluded compensates then, does not have unusual phase diagram so that obtain.
The present invention who comes from another aspect that addresses the above problem is a kind of phase distribution measuring device, and it comprises as lower unit: filter unit, and it carries out low-pass filtering to the image that obtains by magnetic resonance imaging; The location of pixels detecting unit, it detects such location of pixels by the pixel data of each respective pixel of image before the low-pass filtering relatively and the image after the low-pass filtering: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; The PHASE DISTRIBUTION computing unit, it gets rid of the pixel data of detected location of pixels, calculates PHASE DISTRIBUTION according to image before the low-pass filtering or the image after the low-pass filtering; And phase compensation unit, it compensates by the phase place of the location of pixels that is excluded described in the PHASE DISTRIBUTION of estimating to be calculated from the phase place of neighborhood pixels position.
In coming from this present invention on the one hand, by the location of pixels detecting unit relatively before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, so that detect the location of pixels that has phase interference, calculate the excluded phase diagram of the pixel data of these location of pixels by the PHASE DISTRIBUTION computing unit, compensate by phase compensation unit then, phase compensation unit does not have unusual phase diagram by the phase place of the location of pixels estimating from the phase place of neighborhood pixels position to be excluded so that obtain.
The present invention who comes from another aspect that addresses the above problem is a kind of method for correcting phase, and it comprises the steps: the image that obtains by magnetic resonance imaging is carried out low-pass filtering; The pixel data of each respective pixel by image before the low-pass filtering relatively and the image after the low-pass filtering detects such location of pixels: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; The pixel data of getting rid of detected location of pixels calculates PHASE DISTRIBUTION according to image before the low-pass filtering or the image after the low-pass filtering; Phase place by the location of pixels that is excluded described in the PHASE DISTRIBUTION of estimating to be calculated from the phase place of neighborhood pixels position compensates; And utilize the PHASE DISTRIBUTION after the compensation that image is carried out phase correction.
In coming from this present invention on the one hand, compare before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, there is the location of pixels of phase interference in detection, calculating is with the excluded phase diagram of the pixel data of these location of pixels, phase place by the location of pixels estimating from the phase place of neighborhood pixels position to be excluded compensates then, does not have unusual phase diagram so that obtain.Utilize this phase diagram that view data is carried out phase correction then.
The present invention who comes from another aspect that addresses the above problem is a kind of method for correcting phase, and it comprises the steps: the image that obtains by magnetic resonance imaging is carried out low-pass filtering; According to the image calculation PHASE DISTRIBUTION after the low-pass filtering; According to the PHASE DISTRIBUTION of being calculated described low pass filtered wavefront image is carried out phase correction; Once more the image behind the phase correction is carried out low-pass filtering; Calculate new PHASE DISTRIBUTION according to the image after the new low-pass filtering; And carry out new phase correction according to the PHASE DISTRIBUTION of the new calculating image after to phase correction.
In coming from this present invention on the one hand, image after low-pass filtering calculates first phase diagram, carry out phase correction according to the image of this phase diagram before to low-pass filtering, once more the image behind the phase correction is carried out low-pass filtering, from this image calculation second phase diagram, by second phase diagram former image that is undertaken behind the phase correction by first phase diagram is carried out phase correction then.By repeating this phase correction many times, obtain comprising the phase diagram of high order component.
The present invention who comes from an aspect that addresses the above problem is a kind of phase correction unit, and it comprises: filter unit, and it carries out low-pass filtering to the image that obtains by magnetic resonance imaging; The location of pixels detecting unit, it detects such location of pixels by the pixel data of each respective pixel of image before the low-pass filtering relatively and the image after the low-pass filtering: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; The PHASE DISTRIBUTION computing unit, it calculates PHASE DISTRIBUTION by getting rid of the pixel data of detected location of pixels according to image before the low-pass filtering or the image after the low-pass filtering; Phase compensation unit, it compensates by the phase place of the location of pixels that is excluded described in the PHASE DISTRIBUTION of estimating to be calculated from the phase place of neighborhood pixels position; And the phase correction unit, it utilizes the PHASE DISTRIBUTION after the compensation that image is carried out phase correction.
In coming from this present invention on the one hand, by the location of pixels detecting unit relatively before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, so that detect the location of pixels that has phase interference, calculate the excluded phase diagram of the pixel data of these location of pixels by the PHASE DISTRIBUTION computing unit, compensate by the phase place of phase compensation unit then, do not have unusual phase diagram so that obtain by the location of pixels estimating from the phase place of neighborhood pixels position to be excluded.By this phase diagram of phase correction unit by using view data is carried out phase correction then.
The present invention who comes from another aspect that addresses the above problem is a kind of phase correction unit, and it comprises: filter unit, and it carries out low-pass filtering to the image that obtains by magnetic resonance imaging; The PHASE DISTRIBUTION computing unit, it is according to the image calculation PHASE DISTRIBUTION of low-pass filtering; The phase correction unit, it carries out phase correction according to the image of the PHASE DISTRIBUTION of calculating before to described low-pass filtering; And control module, it carries out low-pass filtering to the image behind the phase correction once more by described filter unit, calculate new PHASE DISTRIBUTION by the image of PHASE DISTRIBUTION computing unit after, carry out phase correction once more according to the image of the new PHASE DISTRIBUTION of calculating after phase correction by the phase correction unit according to new low-pass filtering.
In coming from this present invention on the one hand, calculate first phase diagram by the image of PHASE DISTRIBUTION computing unit after the low-pass filtering, carry out phase correction by the phase correction unit according to the image of this phase diagram before to low-pass filtering, image behind the phase correction is carried out low-pass filtering once more, from this image calculation second phase diagram, by second phase diagram image that originally carries out phase correction by first phase diagram is carried out phase correction by the phase correction unit by the PHASE DISTRIBUTION computing unit then.By carrying out repeatedly phase correction like this, finish the phase correction that comprises high order component.By this phase diagram of phase correction unit by using view data is carried out phase correction then.
The present invention who comes from another aspect that addresses the above problem is a kind of MR imaging apparatus, and it comprises: image-generating unit, and it utilizes magnetic resonance to obtain the image of imaging object; Filter unit, it carries out low-pass filtering to the image that obtains by magnetic resonance imaging; The location of pixels detecting unit, it detects such location of pixels by the pixel data of each respective pixel of image before the low-pass filtering relatively and the image after the low-pass filtering: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; The PHASE DISTRIBUTION computing unit, it gets rid of the pixel data of detected location of pixels, calculates PHASE DISTRIBUTION according to image before the low-pass filtering or the image after the low-pass filtering; Phase compensation unit, it compensates by the phase place of the location of pixels that is excluded described in the PHASE DISTRIBUTION of estimating to be calculated from the phase place of neighborhood pixels position; The phase correction unit, the PHASE DISTRIBUTION after its utilization compensation is carried out the phase correction of described image; And image generation unit, it is used to utilize the phase differential of the pixel data of the image behind the phase correction to produce water images and lipides image respectively.
In coming from this present invention on the one hand, by the location of pixels detecting unit relatively before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, so that detect the location of pixels that has phase interference, calculate the excluded phase diagram of the pixel data of these location of pixels by the PHASE DISTRIBUTION computing unit, compensate by phase compensation unit then, phase compensation unit is estimated the phase place of the location of pixels that is excluded from the phase place of neighborhood pixels position, do not have unusual phase diagram so that obtain.By this phase diagram of phase correction unit by using described image is carried out phase correction.Respectively water and lipides are carried out imaging by the view data of image generation unit after according to phase correction.
The present invention who comes from another aspect that addresses the above problem is a kind of MR imaging apparatus, and it comprises: image-generating unit, and it utilizes magnetic resonance to obtain the image of imaging object; Filter unit, it carries out low-pass filtering to the image that obtains by magnetic resonance imaging; The PHASE DISTRIBUTION computing unit, its image after according to low-pass filtering calculates PHASE DISTRIBUTION; The phase correction unit, it carries out phase correction according to the image of the PHASE DISTRIBUTION of being calculated before to described low-pass filtering; Control module, it carries out low-pass filtering once more by the image of described filter unit after to phase correction, calculate new PHASE DISTRIBUTION by the image of PHASE DISTRIBUTION computing unit after, carry out phase correction once more according to the image of the new PHASE DISTRIBUTION of calculating after phase correction by the phase correction unit according to new low-pass filtering; And image generation unit, it utilizes the phase differential of the pixel data of the image behind the phase correction to produce water images and lipides image respectively.
In coming from this present invention on the one hand, by image calculation first phase diagram of PHASE DISTRIBUTION computing unit after the low-pass filtering, carry out phase correction by the phase correction unit according to the image of this phase diagram before to low-pass filtering, image behind the phase correction is carried out low-pass filtering once more, by the PHASE DISTRIBUTION computing unit from this image calculation second phase diagram, then by the phase correction unit by second phase diagram to originally by first phase diagram carry out phase correction image carry out phase correction.By carrying out repeatedly phase correction like this, finish the phase correction that comprises high order component.By this phase diagram of phase correction unit by using view data is carried out phase correction then.Respectively water and lipides are carried out imaging by the view data of image generation unit after according to phase correction.
The present invention who comes from another aspect that addresses the above problem is a kind of MR imaging method, and it comprises the steps: to utilize magnetic resonance to obtain the image of imaging object; The image that obtains by magnetic resonance imaging is carried out low-pass filtering; The pixel data of each respective pixel by image before the low-pass filtering relatively and the image after the low-pass filtering detects such location of pixels: for this location of pixels, the ratio of the value that the value after its low-pass filtering and low-pass filtering are preceding is no more than predetermined ratio; Get rid of the pixel data of the location of pixels that is detected, calculate PHASE DISTRIBUTION according to image before the low-pass filtering or the image after the low-pass filtering; Phase place by the location of pixels that is excluded described in the PHASE DISTRIBUTION of estimating to be calculated from the phase place of neighborhood pixels position compensates; PHASE DISTRIBUTION after the utilization compensation is carried out the phase correction of described image; And the phase differential that utilizes the pixel data of the image behind the phase correction produces water images and lipides image respectively.
In coming from this present invention on the one hand, compare before the low-pass filtering and the pixel data of each respective pixel of the image after the low-pass filtering, so that detect the location of pixels that has phase interference, calculating is with the excluded phase diagram of the pixel data of these location of pixels, then, phase place by the location of pixels estimating from the phase place of neighborhood pixels position to be excluded compensates, and does not have unusual phase diagram so that obtain.Utilize this phase diagram that described image is carried out phase correction.Respectively water and lipides are carried out imaging according to the view data behind the phase correction.
The present invention who comes from another aspect that addresses the above problem is a kind of MR imaging method, and it comprises the steps: to utilize magnetic resonance to obtain the image of imaging object; The image that obtains by magnetic resonance imaging is carried out low-pass filtering; Image according to low-pass filtering calculates PHASE DISTRIBUTION; Carry out phase correction according to the image of the PHASE DISTRIBUTION of calculating before to described low-pass filtering; Image behind the phase correction is carried out low-pass filtering once more, calculate new PHASE DISTRIBUTION, carry out phase correction once more according to the PHASE DISTRIBUTION of the new calculating image after to phase correction according to the image after the new low-pass filtering; Produce water images and lipides image respectively with the phase differential of the pixel data that utilizes the image behind the phase correction.
In coming from this present invention on the one hand, image calculation first phase diagram after the low-pass filtering, carry out phase correction according to the image of this phase diagram before to low-pass filtering, image behind the phase correction is carried out low-pass filtering once more, from this image calculation second phase diagram, then by second phase diagram to originally by first phase diagram carry out phase correction image carry out phase correction.By carrying out repeatedly phase correction like this, finish the phase correction that comprises high order component.Utilize this phase diagram that view data is carried out phase correction then.Respectively water and lipides are carried out imaging according to the view data behind the phase correction.
According to the present invention, even the MR imaging apparatus that the phase distribution measuring method and apparatus that also can calculate precise phase figure when existing local phase to disturb, the method for correcting phase that utilizes the phase diagram that calculates like this and device can be provided and carry out this phase correction.
The present invention also provide make the phase correction comprise high fdrequency component easily method for correcting phase and device, carry out such phase correction MR imaging apparatus, calculate high-quality accurate phase diagram the phase distribution measuring method and apparatus, utilize this calculating phase diagram method for correcting phase and device and carry out the MR imaging apparatus of this phase correction.
Description of drawings
From description, will understand other purposes of the present invention and advantage to the most preferred embodiment of the present invention shown in the accompanying drawing.
Fig. 1 is the concept map of phase diagram.
Fig. 2 is the block scheme according to the device of one embodiment of the present of invention.
Fig. 3 is the block scheme according to the device of one embodiment of the present of invention.
Fig. 4 illustrates the example of the pulse train of being carried out by the device that is shown among Fig. 2 or Fig. 3.
Fig. 5 illustrates the example of the pulse train of being carried out by the device that is shown among Fig. 2 or Fig. 3.
Fig. 6 is the block scheme that is shown in the data processing unit in the device of Fig. 2 or Fig. 3.
Fig. 7 has described the function of the data processing unit that is shown in Fig. 6.
Fig. 8 has described the function of the data processing unit that is shown in Fig. 6.
Fig. 9 is the block scheme that is shown in the data processing unit in the device of Fig. 2 or Fig. 3.
Figure 10 has described the function of the data processing unit that is shown in Fig. 9.
Figure 11 has described the function of the data processing unit that is shown in Fig. 9.
Figure 12 has described the function of the data processing unit that is shown in Fig. 9.
Figure 13 has described the function of the data processing unit that is shown in Fig. 9.
Figure 14 has described the function of the data processing unit that is shown in Fig. 9.
Figure 15 has described the function of the data processing unit that is shown in Fig. 9.
Figure 16 is the block scheme of the data processing unit in the device that is shown among Fig. 2 or Fig. 3.
Figure 17 has described the function of the data processing unit that is shown in Figure 16.
Figure 18 has described the function of the data processing unit that is shown in Figure 16.
Figure 19 has described the function of the data processing unit that is shown in Figure 16.
Embodiment
Describe some embodiments of the present invention in detail with reference to accompanying drawing.Fig. 2 illustrates the block scheme of MR imaging apparatus.Described device is the example of one embodiment of the present of invention.The structure of described device shows the embodiment relevant with device of the present invention.
The operation of described device shows the embodiment relevant with method of the present invention.
As shown in Figure 2, described device comprises magnetic system 100.Magnetic system 100 comprises field coil unit 102, gradient coil unit 106 and RF (radio frequency) coil unit 108.Each of these coil units has the shape of cylinder basically, and they are arranged coaxially to each other.Imaging object 300 is placed on the carriage 500, and moves into and shift out space in the magnetic system 100 by the transfer system (not shown).
Main magnetic field lines coil unit 102 forms the stationary magnetic field in the inner space of magnetic system 100.The direction of stationary magnetic field is arranged essentially parallel to the axle of imaging object 300, promptly forms so-called horizontal magnetic field.Main magnetic field lines coil unit 102 is made of for example superconducting coil.But obviously, it is not limited to superconducting coil, also can be made of general conductive coil or analog.
For the stationary magnetic field intensity gradient is provided, gradient coil unit 106 produces gradient magnetic.The gradient magnetic that produces has three types, be timeslice gradient magnetic (slice gradientmagnetic field), readout gradient magnetic field (read-out gradient magnetic field) and phase encoding gradient magnetic field (phase encode gradient magnetic field), gradient coil unit 106 comprises three gradient coil system (not shown) corresponding to this gradient magnetic of three types.
For 300 underexcitations of the imaging object in being in the space, stationary magnetic field spins (spin), RF coil unit 108 forms high frequency magnetic field.After this, will form high frequency magnetic field and be referred to as transmission RF pumping signal.RF coil unit 108 also receives electromagnetic wave, i.e. magnetic resonance signal, and it is produced by the spin of excitation.RF coil unit 108 comprises transmission coil (not shown) and receiving coil (not shown).Same coil can be used as transmission and receiving coil, perhaps sends coil and receiving coil available dedicated coil.
Gradient-driven unit 130 is connected to gradient coil unit 106.Gradient-driven unit 130 provides drive signal to gradient coil unit 106, so that produce gradient magnetic.Gradient-driven unit 130 comprises three driving circuit (not shown) corresponding to three gradient coils in the gradient coil unit 106.
The outgoing side of data acquisition unit 150 is connected to data processing unit 170.Data processing unit 170 will be from data storage (not shown) storer of data acquisition unit 150 collections.In storer, form data space.Data space comprises two dimension pair upright vane space.Data processing unit 170 conversion two dimension is paid data in the upright vane space, so that the image of reconstruct imaging object 300.
Fig. 3 illustrates the block scheme of MR imaging apparatus.This device is the example of the embodiment of the invention.The structure of described device shows the example of the embodiment relevant with device of the present invention.The operation of described device shows the example of the embodiment relevant with method of the present invention.
The device that is shown in Fig. 3 comprises and is different from the magnetic system 100 ' of installing among Fig. 2.Except magnetic system 100 ', it has the structure identical with the device that is shown in Fig. 2.Identical parts are marked with identical symbol, and its explanation is omitted.
Magnetic system 100 ' comprises main field magnetic cell 102 ', gradient coil unit 106 ' and RF coil unit 108 '.Each of these main field magnetic cells 102 ' and coil unit all comprise separate each other a slit and facing to antithesis.They also have the shape of plate-like basically, and configuration coaxially.Imaging object 300 is placed on the carriage 500, and the inner space that is moved into and shifted out magnetic system 100 ' by the transfer system (not shown).
Main field magnetic cell 102 ' forms the stationary magnetic field in the inner space of magnetic system 100 '.The direction of stationary magnetic field is substantially perpendicular to the axle of imaging object 300, promptly forms so-called quadrature field.Main field magnetic cell 102 ' for example is made of permanent magnet etc., but is not limited to permanent magnet naturally, also can be by superconducting electromagnet or generally conduct electricity electromagnet and constitute.
For the gradient of stationary magnetic field intensity is provided, gradient coil unit 106 ' produces gradient magnetic.The gradient magnetic that produces has three types, and gradient coil unit 106 ' comprises three kinds of gradient coil system (not shown) corresponding to these three types of gradient magnetics.
For the spin of 300 underexcitations of the imaging object in the space, stationary magnetic field, RF coil unit 108 ' sends the RF pumping signal.RF coil unit 108 ' also receives the magnetic resonance signal by the spin generation of excitation.RF coil unit 108 ' comprises transmission coil (not shown) and receiving coil (not shown).Same coil can be used as transmission and receiving coil, perhaps sends coil and receiving coil available dedicated coil.
Fig. 4 illustrates the example of the pulse train that is used for magnetic resonance imaging.This pulse train is the pulse train of spin echo (SE:Spin Echo) method.
Specifically, (1) is 90 degree pulses and the 180 degree pulse trains that are used for SE method RF excitation, and similarly, (2), (3), (4) and (5) are respectively timeslice gradient G s, readout gradient Gr, phase encoding gradient Gp and spin echo MR sequence.90 degree pulses and 180 degree pulses are represented by main signal respectively.Pulse train is advanced from left to right along time shaft t.
As can be seen from this figure, carry out 90 degree spin excitations by 90 degree pulses.At this constantly, application time sheet gradient G s, and the selective excitation of schedule time sheet appears.Behind the preset time of 90 degree excitations, owing to 180 degree pulses produce 180 degree excitations, are spin flip conversion.Go back application time sheet gradient G s here, and the selectivity counter-rotating of identical timeslice occurs.
During the time interval between 90 degree excitations and the spin flip conversion, apply readout gradient Gr and phase encoding gradient Gp.Gr produces phase shift owing to readout gradient.Gp produces phase encoding owing to phase encoding gradient.
Behind spin flip conversion, spin is read out gradient G r phasing again, and produces spin echo MR.Data acquisition unit 150 is collected spin echo MR as viewdata.At period T R (repetition time), pulse train repeats 64 to 512 times.In repeating, phase encoding gradient Gp changes, so carry out different phase encodings at every turn at every turn.Like this, obtain 64 to 512 kinds of viewdatas.
Spin echo MR is the RF signal, and it has with respect to the centrosymmetric waveform of echo.Produce main echo in TE (echo time) back since 90 degree excitations.By suitably selecting TE, can make that the phase differential of water echo and lipides echo is a pi/2.When stationary magnetic field intensity is 0.2T, make that phase differential is that the TE of pi/2 is approximately 2 τ+8.6ms or 2 τ-8.6ms.τ is the time interval that is activated to 180 degree excitations from 90 degree.The spin echo that obtains from the TE of this order of magnitude has enough signal intensities.
Another example that is used for the pulse train of magnetic resonance imaging is shown in Fig. 5.This pulse train is the pulse train of gtadient echo (GRE:Gradient Echo) method.
Specifically, (1) is the α degree pulse train that is used for GRE method RF excitation, and similarly, (2), (3), (4) and (5) are respectively timeslice gradient G s, readout gradient Gr, phase encoding gradient Gp and spin echo MR sequence.The pulse of α degree is represented by main signal.Pulse train is advanced from left to right along time shaft t.
As shown in the drawing, owing to the pulse of α degree produces α degree spin excitation, α is 90 degree or littler.At this constantly, application time sheet gradient G s is so the selective excitation of schedule time sheet occurs.
After the excitation of α degree, the phase encoding that phase encoding gradient Gp spins.Then, readout gradient Gr is at first to the spin phase shift, then the quilt phasing again that spins, and produce gtadient echo MR.Data acquisition unit 150 is collected gtadient echo MR as viewdata.At period T R, this pulse train repeats 64 to 512 times.In repeating each time, phase encoding gradient Gp changes, so carry out different phase encodings each time.Like this, obtain 64 to 512 kinds of viewdatas.
Gtadient echo MR is the RF signal, and it has with respect to the centrosymmetric waveform of echo.Produce main echo in TE (echo time) back from α degree excitation beginning.By suitably selecting TE, can make that the phase differential of water echo and lipides echo is a pi/2.When stationary magnetic field intensity is 0.2T, make that phase differential is that the TE of pi/2 is approximately 8.6ms.The gtadient echo that obtains from the TE of this order of magnitude has enough signal intensities.
The storer of data processing unit 170 is collected the viewdata of being collected by the pulse train of Fig. 4 or Fig. 5.Certainly, be understood that: pulse train is not limited to SE method or GRE method, also can comprise such as fast spin echo (FSE:Fast Spin Echo) method or echo-planar imaging (EPI:Echo Planar Imaging) method.
170 pairs of viewdatas of data processing unit are used two dimension and are paid upright leaf inverse transformation, so that the tomogram of reconstruct imaging object 300.The image of reconstruct is stored in the storer.So far, the 26S Proteasome Structure and Function of described device is the example according to the embodiment of imaging device of the present invention.
According to the image of reconstruct, data processing unit 170 produces the image of water section and the image of lipides part respectively.After this, the image of water section is referred to as water images, and the image of lipides part is referred to as the lipides image.
In the process that produces water images and lipides image, data processing unit 170 calculates PHASE DISTRIBUTION corresponding to the intensity distributions of stationary magnetic field, is phase diagram.Certainly, be understood that: phase diagram not only is used for separating of water and lipides, but also is used for being generally the phase correction of picture.
The example of embodiment.
Fig. 6 is the block scheme from the data processing unit 170 of the viewpoint that produces water images and lipides image respectively.For example, can wait the function that realizes each square among this figure by computer program.Hereinafter this point is identical.
As seeing that data processing unit 170 comprises filter unit 702 from this figure.Filter unit 702 is the examples according to the embodiment of filter unit of the present invention.The image of reconstruct is input to filter unit 702 from the image reconstruction unit 700 of prime.For example, the image of reconstruct can be the image that obtains by with the imaging of standard mirage phantom.The standard mirage phantom only comprises water section.
The pixel data of reconstructed image is provided by plural number.Specifically, pixel data comprises real component and imaginary number component.After this, real component and imaginary number component will be called real part and imaginary part.
In input picture, the phase change that causes owing to the reason the magnetic field bump that changes except the magnetization that causes imaging object, by lipides, move the afterimage that causes or the combination of noise greatly or these factors by blood circulation or health, when the phase place of pixel data was interfered partly, the vector of expression complex pattern data may have the various phase places shown in the regional A that for example resembles Fig. 7.Fig. 7 is the one-dimensional sequence pixel data.Be simplified illustration, the signal intensity of supposing pixel data is constant.
The image of this input at filter unit 702 through low-pass filtering.For example carry out low-pass filtering by moving average process.Except that moving average, for example, can be to the suitable weighting of pixel data application such as Gaussian distribution.
Because low-pass filtering, come the calculating pixel data with the form of the mean value of the neighborhood pixels data of both sides predetermined quantity, so each pixel data will resemble example as shown in Figure 8.Specifically, at regional A, the phase place of pixel data is different from the phase place of surrounding pixel data greatly, so signal intensity considerably descends owing to moving average.Outside regional A, except that next-door neighbour's pixel data, in fact there is not such difference.
About these pixel datas, location of pixels detecting unit 704 detects the location of pixels that those amplitudes have reduced.Location of pixels detecting unit 704 is embodiment according to location of pixels detecting unit of the present invention.When detecting location of pixels, just check input imagery.Carry out the detection of location of pixels by detecting the location of pixels that satisfies following equation condition:
Or
Wherein E, e are threshold values.
Utilize above-mentioned equation, the relatively pixel data of the respective pixel of image before the filtering and filtered image, and the location of pixels that reduces to have surpassed preset limit value of detection signal strength.As a result, can detect the location of pixels that belongs to regional A, promptly have a location of pixels of phase interference.
For example, threshold value E, e are defined as the statistical value of standard deviation of the value of formula (1) based on all pixel datas or formula (2).Another kind method is that they are the value of determining based on past experience.Have again, can suitably adjust according to the result to them.
Detected like this location of pixels information is input to PHASE DISTRIBUTION computing unit 706.The image of input also is input to PHASE DISTRIBUTION computing unit 706.The image that is input to PHASE DISTRIBUTION computing unit 706 can be the image of filter unit 702 outputs.PHASE DISTRIBUTION computing unit 706 is embodiment according to PHASE DISTRIBUTION computing unit of the present invention.
The phase place of each pixel data of PHASE DISTRIBUTION computing unit 706 calculating input images.Calculate phase place by the real part of calculating complex pattern data and the arc tangent of imaginary part.In this course, getting rid of above-mentioned location of pixels calculates.Like this, obtain not having the PHASE DISTRIBUTION of the data of those location of pixels that have phase interference.
About this PHASE DISTRIBUTION, there is not the part of phase data to carry out phase correction by 708 pairs of phase compensation units.Phase compensation unit 708 is embodiment according to phase compensation unit of the present invention.Carry out phase compensation by method of interpolation.Method of interpolation can be interpolation or phase-interpolation.For interpolation calculation, can use function of first order, higher-order function or splines according to convenient.
Like this, obtain the complete PHASE DISTRIBUTION of described data.According to this PHASE DISTRIBUTION, form unit 710 by phase diagram and form phase diagram.When forming phase diagram, carry out the phase place uncoiling.When having eliminated the phase interference in the PHASE DISTRIBUTION, can accurately carry out uncoiling, and can obtain correct phase diagram.
Phase diagram is stored in phase diagram storer 712.In phase correction unit 714, be used to the phase correction of reconstructed image by the phase diagram of phase diagram storer 712 storages.Phase correction unit 714 will be by the reconstructed image of phase correction, so that carry out phase correction from image reconstruction unit 700 inputs.Utilize the phase place that the phase place of respective pixel is proofreaied and correct described pixel data in the phase diagram.
The complex pattern of phase correction is input to water/lipides separative element 716.Water/lipides separative element 716 is the examples according to the embodiment of image formation unit of the present invention.Water/lipides separative element 716 utilizes the real part of the complex pattern of phase correction to produce water images and utilizes the imaginary part of the complex pattern of phase correction to produce the lipides image.Like this, obtain accurate water images and lipides image.The water images that produces is stored in the water images storer 718, and the lipides image is stored in the lipides video memory 720.
Fig. 9 illustrates from the block scheme of the data processing unit 170 of the viewpoint that produces water images separately and lipides image.For example, can wait the function that realizes each square among this figure by computer program.If the heterogeneity of stationary magnetic field is non-linear, the data processing unit 170 that then is shown in this figure carries out phase correction by the respective phase figure that comprises high order component.In brief, high order component and the low order component with the heteropical non-linear corresponding phase diagram in stationary magnetic field will be referred to as high-order phase place and low order phase place.
As shown in this Fig, data processing unit 170 comprises filter unit 724.Filter unit 724 is identical with above-mentioned filter unit 702.From the image of image reconstruction unit 700 or the image of the phase correction of describing after a while be input to filter unit 724 via converting unit 722.Come the conversion of control transformation unit 722 by control module 732.
The image of 724 pairs of inputs of filter unit carries out low-pass filtering.Filter unit 724 is the examples according to the embodiment of filter unit of the present invention.The degree of low-pass filtering is adjusted by control module 732.The degree of low-pass filtering also can utilize moving average to be adjusted by data number and weighting.Controller 732 is embodiment according to filtering adjustment unit of the present invention.
Because this low-pass filtering obtains resembling routine PHASE DISTRIBUTION as shown in Figure 10 or resembles the level and smooth PHASE DISTRIBUTION shown in Figure 10 in reconstructed image.This PHASE DISTRIBUTION only comprises single order or contiguous low order phase place, and does not comprise the high-order phase place.For explaining that conveniently PHASE DISTRIBUTION deteriorates to single order in Figure 10 and Figure 11.For the figure of back, this point is identical.
For the reconstructed image of low-pass filtering, form unit 726 by phase diagram and form phase diagram.708 structure can join the phase diagram formation unit 726 from location of pixels detecting unit 704 to phase compensation unit among Fig. 5, and is revising phase interference part back formation phase diagram.
Phase diagram formation unit 726 is embodiment according to phase calculation unit of the present invention.It is identical with above-mentioned phase diagram formation unit 710 that phase diagram forms unit 726.When forming phase diagram, rollback is partly carried out uncoiling.
The PHASE DISTRIBUTION of the image of low-pass filtering is as shown in Figure 11, and obtains resembling phase diagram shown in Figure 12 thus.Utilize this phase diagram that input picture is carried out phase correction by phase correction unit 728.Phase correction unit 728 is embodiment according to phase correction of the present invention unit.Phase correction unit 728 is identical with above-mentioned phase correction unit 714.
The PHASE DISTRIBUTION of the input picture of phase correction resembles example as shown in Figure 13.Shown in this figure like that, the single order or the low order phase place of input picture are carried out phase correction, stay the high-order phase place.The high-order phase place that stays comprises the high-order phase place that the non-linearity because of the stationary magnetic field causes.
Image with phase correction of this PHASE DISTRIBUTION turns back to filter unit 724 via converting unit 730 and converting unit 722, carries out low-pass filtering once more at that.Adjust the low-pass filtering degree by controller 732.With the low-pass filtering degree arrange be weaker than next-door neighbour former case the low-pass filtering degree.The low-pass filtering degree is weakened.
Because this low-pass filtering, the PHASE DISTRIBUTION of image for example shown in Figure 13 becomes as shown in Figure 14.Figure 14 comprises and depends on the high-order phase place that low-pass filtering weakens degree.
Phase diagram formation unit 726 forms phase diagram from the image of this low-pass filtering.The phase diagram that obtains thus is identical with phase diagram shown in Figure 14.Phase correction unit 728 now utilizes this phase diagram that the image of phase correction is carried out phase correction once more.
The PHASE DISTRIBUTION of the image of phase correction has been finished the phase correction of high-order phase place, for example resembled shown in Figure 15.Can proofread and correct the high-order phase place that the non-linearity by the stationary magnetic field causes like this.
If the correction of the high-order phase place that also will stay image in this one-level.Image with phase correction turns back to filter unit 724 via converting unit 722 once more.Further reduce the filtering degree of filter unit, carry out low-pass filtering, and utilize from the image of filtering calculate phase diagram carry out the third phase bit correction.Repeat the number of times that this handles needs.In other words, form described phase diagram circularly and utilize this phase diagram to carry out phase correction.The parts that comprise controller 732 and converting unit 722,730 are according to control module of the present invention
Embodiment.
In each situation, progressively weaken the low-pass filtering degree.On the contrary, the low-pass filtering degree can be established at first a little less than, and in each situation, progressively strengthen the low-pass filtering degree.In order to strengthen the low-pass filtering degree, for example can increase the data number of moving average.In each situation, the low-pass filtering degree also can be identical.
The image that can show phase correction in any time during the above-mentioned repetition.Like this, can check the degree of phase correction at any time, carry out the phase correction that is fit to more like this.
At last, the image with phase correction is input to water/lipides separative element 716 via converting unit 730.Water/lipides separative element 716 forms water images and lipides image respectively, and they are stored in water images storer 718 and the lipides video memory 720.Carry out phase correction,, obtain accurate water images and lipides image like this up to high order component.
When the image that is obtained by imaging object 300 is used as original image and calculates phase diagram, because above-mentioned pulse train, water images and lipides image have the phase differential of pi/2, therefore at the point of corresponding lipides image, because the heterogeneity of stationary magnetic field, described phase diagram has the phase place of having added pi/2.
If carry out phase correction with such phase diagram, even the phase differential of water images and lipides image is corrected, the also image of water that no longer may obtain separating and lipides.Therefore, when calculate during the phase diagram of the image that obtains by imaging object 300, carry out the processing of back.
From the viewpoint of the phase diagram of computed image, Figure 16 illustrates the block scheme of data processing unit 170, and water images and lipides image have the phase differential of pi/2 in the described image.As shown in the drawing, data processing unit 170 comprises energy (power) image formation unit 902 and PHASE DISTRIBUTION computing unit 904.The image of reconstruct is input to energy image formation unit 902 and PHASE DISTRIBUTION computing unit 904.
Energy image formation unit 902 is to the power of each pixel calculated complex data, and form image that this power wherein is considered to pixel value, be the energygram picture.PHASE DISTRIBUTION computing unit 904 calculates the PHASE DISTRIBUTION of the image of reconstruct.Figure 17 (a) illustrates the synoptic diagram of PHASE DISTRIBUTION.This illustrates the situation when PHASE DISTRIBUTION figure is one dimension figure when tomogram comprises its water images of encirclement and lipides image.
If the supposition stationary magnetic field is uniform, when the phase place of water images is 0, described one dimension PHASE DISTRIBUTION figure (after this being called PHASE DISTRIBUTION simply) should have the profile shown in this figure dot-and-dash line, if the stationary magnetic field for example has the heterogeneity of straight slope, then PHASE DISTRIBUTION will by shown in the solid line like that.
PHASE DISTRIBUTION is input to phase place quadrupler 906.Phase place quadrupler 906 with each phase multiplication in the PHASE DISTRIBUTION with 4.The result obtains the PHASE DISTRIBUTION that Figure 17 (b) illustrates.As shown in the drawing, make the phase differential between water and the lipides become 2 π owing to four times, so both have identical phase place.It should be noted that rollback in PHASE DISTRIBUTION, to occur, and occur the interruption of phase place or sharply variation on the border of water and lipides.
This PHASE DISTRIBUTION is input to complex pattern forms unit 908.Also the energygram with energy image formation unit 902 looks like to be input to complex pattern formation unit 908.Complex pattern forms unit 908 and looks like to form complex pattern according to PHASE DISTRIBUTION and energygram.
Calculating is as the real part of the complex pattern of the cosine of energy view data.Calculating is as the imaginary part of the complex pattern of the sine of energy view data.Being used to calculate cosine is the phasing degree with sinusoidal angle.
Complex pattern is input to PHASE DISTRIBUTION computing unit 912 via low-pass filter 910.PHASE DISTRIBUTION computing unit 912 usefulness form PHASE DISTRIBUTION through the complex pattern of low-pass filtering.Because low-pass filtering, in PHASE DISTRIBUTION, eliminated the phase place that is shown in Figure 18 (a) and interrupted and sharply change, for example as shown in Figure 18 (b).
This PHASE DISTRIBUTION is input to phase place separates roll unit 914.Phase place is separated the phase place that 914 pairs of roll units have a rollback that Figure 19 (a) illustrates and is carried out uncoiling so that it resemble shown in Figure 19 (b) by uncoiling.
The PHASE DISTRIBUTION of uncoiling is input to 1/4 phase multiplier 916.1/4 phase multiplier 916 with the input phase multiplication with 1/4.As a result, obtain being shown in the PHASE DISTRIBUTION of Figure 19 (c).The corresponding PHASE DISTRIBUTION when imaging object 300 is water of this PHASE DISTRIBUTION.Therefore, this PHASE DISTRIBUTION is represented the stationary magnetic field intensity distributions, is the heterogeneity of stationary magnetic field.
In Fig. 5, replace this processing, the phase diagram that can not influenced by lipides with the processing of PHASE DISTRIBUTION computing unit 706 and the processing that in Fig. 8, forms unit 726 with phase diagram.
Can constitute far-ranging many different embodiment of the present invention and not break away from the spirit and scope of the present invention.Should be pointed out that except in the accompanying Claim book, defining the specific embodiment that the invention is not restricted to describe in this instructions.
Claims (13)
1. method for correcting phase, it comprises the steps:
The image that obtains by magnetic resonance imaging is carried out low-pass filtering, to produce the low-pass filtering image;
Calculate PHASE DISTRIBUTION according to described low-pass filtering image, the PHASE DISTRIBUTION of being calculated to provide;
Come the image before the described low-pass filtering is carried out phase correction according to the PHASE DISTRIBUTION of described calculating, so that the phase correction image to be provided;
Described phase correction image is carried out low-pass filtering, so that new low-pass filtering image to be provided;
Calculate new PHASE DISTRIBUTION according to described new low-pass filtering image, so that new calculating PHASE DISTRIBUTION to be provided; And
Come described phase correction image is carried out phase correction according to described new calculating PHASE DISTRIBUTION.
2. the method for claim 1, it is characterized in that: all above-mentioned steps periodically repeat.
3. the method for claim 2 is characterized in that: little by little weaken described low-pass filtering when carrying out described low-pass filtering at every turn.
4. the method for claim 2 is characterized in that: little by little strengthen described low-pass filtering when carrying out described low-pass filtering at every turn.
5. phase correction unit, it comprises:
Filter unit is used for the image that obtains by magnetic resonance imaging is carried out low-pass filtering;
Computing unit is used for calculating PHASE DISTRIBUTION according to described low-pass filtering image;
Correcting unit is used for coming the image before the described low-pass filtering is carried out phase correction according to the PHASE DISTRIBUTION of described calculating; And
Control module is used for making and by described filter described phase correction image is carried out low-pass filtering once more, calculate new PHASE DISTRIBUTION by described computing unit according to described new low-pass filtering image, and come described phase correction image is carried out phase correction according to described new calculating PHASE DISTRIBUTION by described correcting unit once more.
6. the device of claim 5, it is characterized in that: described control module makes described filter unit, described computing unit and the periodically repetitive operation of described correcting unit.
7. the device of claim 6 is characterized in that: described control module makes described filter unit that the low-pass filtering that weakens gradually is provided when each filtering.
8. the device of claim 6 is characterized in that: described control module makes described filter unit that the low-pass filtering of strengthening gradually is provided when each filtering.
9. MR imaging apparatus, it comprises:
Image-generating unit is used to utilize magnetic resonance imaging to obtain the image of imaging object,
Filter unit is used for the described image that obtains by magnetic resonance imaging is carried out low-pass filtering, so that the low-pass filtering image to be provided;
Computing unit is used for calculating PHASE DISTRIBUTION according to described low-pass filtering image, the PHASE DISTRIBUTION of being calculated to provide;
Correcting unit is used for coming the described image before the described low-pass filtering is carried out phase correction according to the PHASE DISTRIBUTION of described calculating, so that the phase correction image to be provided;
Control module, be used for making and by described filter described phase correction image carried out low-pass filtering once more, calculate new PHASE DISTRIBUTION by described computing unit according to new low-pass filtering image, and come described phase correction image is proofreaied and correct according to new calculating PHASE DISTRIBUTION by described correcting unit once more; And
Generation unit is used to utilize the phase differential of the pixel data of phase correction image to produce water images and lipides image respectively.
10. the device of claim 9, it is characterized in that: described control module makes described filter unit, described computing unit and described correcting unit cycling.
11. the device of claim 10 is characterized in that: also comprise the unit that is used to adjust described filter unit, make, weaken low-pass filtering gradually for each filter step.
12. the device of claim 10 is characterized in that: also comprise the unit that is used to adjust described filter unit, make low-pass filtering strengthen gradually with each filter step.
13. a MR imaging method, it may further comprise the steps:
Utilize magnetic resonance to obtain the image of imaging object,
The described image that obtains by magnetic resonance imaging is carried out low-pass filtering;
Calculate PHASE DISTRIBUTION according to described low-pass filtering image;
Come the image before the low-pass filtering is carried out phase correction according to the PHASE DISTRIBUTION of being calculated that step formerly obtains;
The phase correction image that step is formerly obtained carries out low-pass filtering;
The new new PHASE DISTRIBUTION of low-pass filtering image calculation according to step acquisition formerly;
New calculating PHASE DISTRIBUTION according to step acquisition is formerly carried out phase correction to the phase correction image once more; And
Utilize the phase differential of the pixel data of the phase correction image that step formerly obtains to produce water images and lipides image respectively.
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| CN102193076A (en) * | 2010-02-03 | 2011-09-21 | 西门子公司 | Method and magnetic resonance device to determine a background phase curve |
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| JP4901031B2 (en) * | 2001-08-28 | 2012-03-21 | ジーイー・メディカル・システムズ・グローバル・テクノロジー・カンパニー・エルエルシー | Phase contradiction detection method and apparatus, phase contradiction elimination method and apparatus, and magnetic resonance imaging apparatus |
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|---|---|---|---|---|
| CN102193076A (en) * | 2010-02-03 | 2011-09-21 | 西门子公司 | Method and magnetic resonance device to determine a background phase curve |
| CN102193076B (en) * | 2010-02-03 | 2016-02-03 | 西门子公司 | For determining the method that background phase changes and magnetic resonance device |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1094333A2 (en) | 2001-04-25 |
| EP1094333B1 (en) | 2007-01-10 |
| DE60032848T2 (en) | 2007-10-25 |
| KR20010060189A (en) | 2001-07-06 |
| US6466016B1 (en) | 2002-10-15 |
| CN1327239C (en) | 2007-07-18 |
| CN1920592B (en) | 2011-06-15 |
| DE60032848D1 (en) | 2007-02-22 |
| CN1305113A (en) | 2001-07-25 |
| JP2001120516A (en) | 2001-05-08 |
| EP1094333A3 (en) | 2003-01-29 |
| JP3454760B2 (en) | 2003-10-06 |
| KR100742459B1 (en) | 2007-07-25 |
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